I2PSnark "forgets" data location if not available

Description

I'm running I2P 0.9.21 under Linux.

I added a torrent to I2PSnark and set the data location to a location that's not mounted by default (/run/media/me/extdata). The torrent started downloading.

When I reboot my PC, the location is not mounted. When I now start I2P before mounting the disk, the torrent goes into the state stopped, but also resets the data location to ~/.i2p/i2psnark/. Thus it would start downloading the torrent again, even if it was already completed.

To undo this, I manually have to go into ~/.i2p/i2psnark.config.d/ and find the correct .config file to set the location to /run/media/me/extdata again.

It was too hard to keep a list of broken snarks. Fix is just to skip the cleanupTorrentStatus() call completely if any torrent errors out. If the errors are resolved, we will call it at the next i2psnark startup.

It will now attempt to add the torrent once a minute in each DirMonitor? pass, and log an error on failure. When the error is resolved, the torrent will be added without forgetting the location.